Free shipping on all orders over $75. Shop Now 📦
INCI Name: Stearic Acid
Chemical Formula: C₁₈H₃₆O₂
CAS Number: 57-11-4
EINECS Number: 200-313-4
Source and Production
Stearic acid is typically derived from animal fats (e.g., tallow) or vegetable oils (such as palm oil or coconut oil) through a process known as hydrolysis, followed by purification. Plant-derived stearic acid is widely used in vegan and cruelty-free cosmetic formulations.
Functions and Applications
Stearic acid is versatile across multiple industries, including cosmetics, pharmaceuticals, food, and manufacturing. In cosmetic and personal care products, it serves several important functions:
Emulsifier: Helps stabilize oil-in-water emulsions by thickening and co-emulsifying with ingredients like glyceryl stearate or PEGs.
Thickener & Viscosity Enhancer: Adds body to lotions, creams, and scrubs.
Hardener: Used in soaps and stick formulations to increase hardness and improve structural integrity.
Physical and Chemical Properties
Property | Value |
Appearance | White, waxy solid or flakes |
Melting Point | ~69–70°C (156–158°F) |
Boiling Point | ~361°C (682°F) |
Solubility | Insoluble in water; soluble in oils and alcohol |
Odor | Odorless to faint fatty odor |
pH (in solution) | ~5–6 (mildly acidic) |
Compatibility and Considerations
pH Range: Best used in formulations with a pH of 4.5–8.
Incompatibilities: May thicken excessively or destabilize emulsions if used at high concentrations without proper emulsifier support.
Typical Usage Rate: 1–5%, depending on the desired thickening or structuring effect.
Melting Advice: Must be melted with the oil phase and thoroughly blended for best results.
Common Uses in Cosmetics
Lotions and creams
Body butters
Cleansers and facial washes
Bar soaps and syndet bars
Emulsified sugar scrubs
Deodorant sticks and balms
Alternatives & Substitutions
Stearic acid is a fatty acid, thickener, hardener, and co-emulsifier in cosmetic and personal care products. When substitution is necessary—whether due to sourcing issues, formulation needs, or ethical considerations—there are several suitable alternatives, depending on the desired function.
🔁 Functional Substitutes (Based on Use Case):
Use Case | Common Alternatives | Notes |
Thickening / Structuring Agent | Cetyl Alcohol, Cetearyl Alcohol, Behenic Acid | Fatty alcohols can provide similar viscosity and glide but are less waxy. |
Hardening (e.g., soap or sticks) | Palmitic Acid, Candelilla Wax, Carnauba Wax | Palmitic acid is a close analog; waxes offer hardness but a different texture. |
Co-Emulsifier | Glyceryl Stearate, Ceteareth-20, Sodium Stearoyl Lactylate | Helps stabilize emulsions when stearic acid is removed. |
Opacifier / Bodying Agent | Myristic Acid, Lauric Acid (in small amounts) | Lighter fatty acids can work for lighter creams, but melt at lower temps. |
Vegan Alternative | Vegetable-Derived Stearic Acid (Palm-free or RSPO-certified), Hydrogenated Soybean Oil | Ensure sourcing aligns with vegan or palm-free claims. |
Considerations When Substituting:
Melting Point: Alternatives may have different melting points, impacting processing temperatures.
Texture & Skin Feel: Waxes can impart a firmer or waxier feel than stearic acid; fatty alcohols often feel silkier or drier.
Emulsion Stability: Stearic acid contributes to both viscosity and emulsion stability. When replacing, a co-emulsifier may be necessary.
pH Compatibility: Always confirm pH tolerance of the substitute within your formulation range.
🌱 Sustainable & Vegan Alternatives
If you're avoiding palm oil or animal byproducts, consider these:
Palm-Free Stearic Acid: Derived from rapeseed, soybean, or sunflower oil.
Sunflower Wax or Rice Bran Wax: For hardening and thickening in natural balms and scrubs.
Hydrogenated Vegetable Oils: Can provide similar body and structure to plant-based oils.
🧪 Tip for Formulators:
When substituting stearic acid, start with a small batch and adjust by functionality, not just by weight. For example:
If replacing with cetyl alcohol, reduce the usage slightly and test emulsion viscosity.
If replacing with palmitic acid in soap making, account for different saponification values.